Re: Terry's DRSSTC - Frequency/Pulse Width Controller

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Ward <steve.ward@xxxxxxxxx>

Hey Terry,

I think you already said what "my" solution to the non-linear
frequency of the 555.  My controllers often use a "coarse" and "fine"
pot for the BPS.  The coarse is usually like 1MEG and the fine is like
50K.  The "fine" really controls the upper frequencies, and the
"coarse" is just there to get the timings right.

Also, for the pulse width control, you might find that you dont even
want a trimmer in series with your "on the fly" PW adjustment pot.  At
least in my case i wanted to have that single turn pot go to "zero",
so i did not add any series resistance with it.  So it seems best to
base the timing components around that pot (which will likely be 1K or
5K) and the timing cap (usually 47nF to 100nF).

Anyway, just some suggestions i had.


> BTW - Rather than being on the "bleeding edge" of this DRSSTC stuff I am
> now "following" :o)))  It's sort of nice :-)))  Many thank to those that
> figured the hard stuff out!!!  I really think the DRSSTC will change
> "everything" in our hobby!!!

Its hard to say who contributed once... but things do seem to be
progressing as some of us eventually end up with coils that dont blow
up IGBTs every 5 minutes :-)

I started putting metal caging around the base of my coils.  As long
as the grid of the fence is small (i use .25" squares) then there is
no noticable loss, but if you use stuff with big squares, they all act
like little shorted turns and suck up current from the primary!!
Check out my 2 coils that use this now (pics at the BOTTOM of each
page)

http://www.stevehv.4hv.org/DRSSTC.5.htm

http://www.stevehv.4hv.org/DRSSTC3.htm

Seeya,

Steve

>
> Cheers,
>
>        Terry
>
>